1. Field of the Invention
The present invention relates to the construction of a powertrain for an automotive vehicle of a type including at least an engine and a transmission which are transversely mounted and arranged parallel to each other in an engine room of the body of the vehicle.
2. Description of Related Art
In automotive vehicles, such as four-wheel drive vehicles and front engine-front drive (FF) vehicles, the design of a powertrain primarily depends upon whether an engine and a transmission are mounted, as one powertrain unit, transversely or lengthwise in an engine room of the vehicle body. In a transversely mounted powertrain arrangement, if both an engine and a transmission are aligned, i.e., mounted in line, the overall length of the entire powertrain becomes large and the powertrain is not practical. Because of this, some powertrains are formed so that a transmission is positioned behind an engine. A power transfer means, such as a gear train and a chain, is used to operationally couple the engine and the transmission to each other. Such a transversely mounted powertrain is known from, for instance, Japanese patent application No 63-146,130, entitled "Power Transmitting Apparatus," filed on Jun. 14, 1988 and laid open to the public as Japanese Unexamined Patent Publication No. 1-316,561, on Dec. 21, 1989.
Typically, since an engine clutch, which must be fluid-tightly sealed, is positioned between a transmission and a power transfer arrangement, lubrication oil is introduced through oil passages provided separately in the transmission and the power transfer arrangement for lubricating rotary elements, such as bearings, of the transmission and the power transfer arrangement. Providing such separate lubrication oil passages results in a complicated oil circulating passage system and increases the cost of powertrain.
In order for powertrains to be compactly constructed, some powertrains have a single unitized powertrain case in which at least an engine and a transmission are housed. In what is referred to as a "unitized" powertrain, a single unitized powertrain case is designed so that an interface between two case components includes a center axis of rotation of an output shaft of the transmission. It is, therefore, possible to grasp the output shaft, which is generally great in length, between and by the two case components. Such a unitized powertrain is known from, for instance, Japanese Utility model Publication No. 48-22,886. However, such a unitized powertrain limits possibilities for arranging or locating a transmission in an engine room.
In attempting to arrange a transmission in a desirable manner, it is possible to split a long output shaft of the transmission into two or more shaft portions. However, each shaft portion needs more than one bearing and associated parts in order to be supported for rotation with a sufficiently high supporting rigidity. This leads to an increased cost.